CBSE Questions for Class 9 Physics Force And Laws Of Motion Quiz 2 - MCQExams.com

What is the magnitude of the pseudo force on a driver by the racing car he operates,  as it accelerates horizontally along a straight line from rest to $$60\ ms^{-1}$$ in $$ 8.0\ s$$?
(mass of driver $$= 80\ kg)$$
  • $$0.6\ kN$$
  • $$0.78\ kN$$
  • $$1.4\ kN$$
  • $$1.0\ kN$$
When an athlete takes part in a long jump he runs for a while and then jumps. This is because:
  • inertia of motion helps him to take a longer jump.
  • running for a time makes him alert.
  • it helps him to focus on the point of jump.
  • he can apply more force for the jump after running.
Two persons are applying forces on two opposite sides of a moving cart. The cart still moves with the same speed in the same direction. What do you infer about the magnitudes and direction of the forces applied.
  • Force in the direction opposite to the motion is zero
  • Force in the direction opposite to the motion is greater
  • Both are Pushing with equal and opposite force
  • Force in the direction of motion is greater.
Water sprinkler used for grass lawns begins to rotate as soon as the water is supplied. It is based on which law?
  • Newton's first law of motion
  • Newton's second law of motion
  • Newton's third law of motion
  • First law of thermodynamics
A boat with a sail, has an electric fan inside. When the fan starts, the boat
  • Cannot move
  • Can move
  • Moves depending on wind directions
  • Moves depending on the speed of the fan
An object $$A$$ of mass of $$0.1 kg$$ exerts a force of $$1 N$$ on a body $$B$$. Then the acceleration of the body $$A$$ is how much in $$m  s^{-2}$$:
  • Zero
  • $$10$$
  • $$-10$$
  • $$-5$$
When a net force acts on an object, then the object will accelerate in the direction of force with an acceleration proportional to the
  • force on the object
  • velocity of the object
  • mass of the object
  • inertia of the object
The ratio of force and acceleration is
  • mass
  • impulse
  • momentum
  • none of these
The SI unit of force is:
  • Dyne
  • Gram-weight
  • Newton
  • None of these
A rocket works on the which law of motion?
  • Newton's first law
  • Newton's second law
  • Newton's third law
  • None of these
When a body is in translatory equilibrium
  • the body is definitely at rest
  • the body is definitely in the state of uniform motion
  • the body will be either at rest or in the state of uniform motion
  • none of these
A $$10\ N$$ force applied on a body produces in it an acceleration of $$2\ ms^{-2}$$. The mass of the body is ________.
  • $$2\ kg$$
  • $$5\ kg$$
  • $$10\ kg$$
  • $$20\ kg$$
Action and reaction
  • always act on two different bodies
  • are equal in magnitude
  • act in opposite directions
  • All the above
While opening a tap with two fingers, the forces applied are :
  • Equal in magnitude
  • Parallel to each other
  • Opposite in direction
  • All the above
When a body is stationary, then :
  • There is no force acting on it.
  • The body is in vacuum.
  • The forces acting on it is not in contact with it.
  • The net forces acting on it balances each other.
Which of the following statements are correct for action and reaction forces?
  • These act on two different bodies
  • These are equal in magnitude but opposite in direction.
  • These act on a single body.
  • These are necessary to explain reaction in third law.
Newton's first law of motion gives the concept of inertia.
  • True
  • False
A canon after firing recoils due to Newton's third law of motion.
  • True
  • False
Inertia of a body has direct dependence on :
  • Velocity
  • Volume
  • Mass
  • Density
A man getting down from a running bus falls forward :
  • as the forward movement of bus tries to pull the man forward
  • due to inertia the upper part of the body moves in the forward direction while feet come to the rest as soon as they touch the road
  • as he leans forward as a matter of habit
  • due to the combination effect of all the three factors stated in $$(A),(B)$$ and $$(C)$$
Which of the following is NOT attributable to application of force?
  • Rowing of a boat
  • Bursting of a balloon while blowing
  • Pedaling a cycle
  • Catching a moving cricket ball
A $$60\ kg$$ man pushes a $$40\ kg$$ man by a force of $$60\ N$$. The $$40\ kg$$ man has pushed the other man with a force of:
  • $$40\ N$$
  • $$0$$
  • $$60\ N$$
  • $$20\ N$$
In which of the following events a pushing force is involved?
  • Badminton
  • Javelin
  • Archery
  • Bowling
When we kick a stone, we get hurt. Due to which one of the following properties does it happens?
  • velocity
  • momentum
  • inertia
  • reaction forces
A man is standing on a platform of a balance and takes a quick step, then his weight:
  • decreases
  • increases
  • remains unchanged
  • first increases and then decreases
A gun requiring the support of shoulder shows intensive recoil when fired with:
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  • the butt held tightly with the shoulder.
  • the butt held loosely against the shoulder.
  • butt held loosely or tightly against the shoulder.
  • a bullet of greater mass.
A lead block is suspended from your hand by a string. The reaction due to the force of gravity on the block is the force exerted by :
  • The string on the block
  • The block on the string
  • The string on the hand
  • The block on Earth
A car travels towards the east with a certain constant velocity. The direction of net force on the car is
  • towards east
  • towards west
  • towards up
  • Zero
Choose the correct statement(s)
  • Motion necessarily takes place along the direction of force
  • If no force acts, the body is at rest
  • A body in motion, need not be acted upon by a force
  • A change in speed is always there, whenever a force is applied on the moving body
What is meant by the term inertia?
  • There is natural tendency for objects to resist changes in their state of motion.
  • A measure of an object's resistance to changes in a rotation direction.
  • A force is a push or a pull that acts upon an object as a results of its interaction with another object.
  • A measurement of the amount of matter something contains.
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